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Evidence for an immunoglobulin-dependent antigen-specific helper T cell.

Evidence from various systems suggests that thymus-derived lymphocytes can affect the quality of antibody responses by recognizing various portions of the immunoglobulin receptor of bone-marrow-derived thymus-independent lymphocytes. A model for this process is proposed involving two antigen-specific mature T helper cells, one of which also is specific for immunoglobulin determinants. These two cells act synergistically. Evidence from adoptive secondary antibody responses demonstrates that both cells are antigen-specific T cells and that the immunoglobulin-recognizing T helper cell is absent from experimentally agammaglobulinemic mice. This cell is termed an "immunoglobulin-dependent T cell" because its activation requires the presence of immunoglobulin.

Animals

A simple and efficient method for preparation of immunoelectrophoretically pure guinea pig IgM and isolation of monospecific anti-IgM antibodies.

This report describes experimental conditions developed for the rapid and efficient preparation of guinea pig IgM in a purified form and in high yield. A combined immunization procedure had to be designed to obtain sufficiently high IgM concentrations in guinea pig serum. The isolation procedure includes precipitation at low pH, followed by sedimentation at 110,000 g and reverse flow gel chromatography on Sephades G-200. Furthermore,we describe in detail the isolation of relatively large amounts of pure and specific anti-guinea pig mu-chain antibodies by immunoaffinity chromatography.

Animals

Immune response to phosphorylcholine. I. Characterization of the epitope-specific antibody.

The antibodies to phosphorylcholine induced in BALB/c mice were isolated and studied with a variety of biochemical and immunochemical methods. Analysis of the idiotype and the hapten-binding specificities showed no differences to the phosphorylcholine-binding myeloma protein TEPC 15, indicating a high degree of homogeneity. However, disc electrophoresis, isoelectric focusing and amino acid composition data indicated large differences in the structure of anti-phosphorylcholine antibody and TEPC 15. By these criteria the anti-phosphorylcholine antibodies from BALB/c mice are of oligoclonal origin.

Amino Acid Sequence

Chicken high molecular weight immunoglobulin (IgM) allotypes: localization on the heavy chains and proposed nomenclature.

An alloantiserum recognizing a genetic marker (CM-1.4) on chicken 17S Ig was generated by immunizing jungle fowl with Salmonella O-anti-Salmonella O (UCD 3) agglutinates. Specificities CM-1.4 and M1a were present on 7S subunits and H chains based on their ability to inhibit in RIA the binding of alloantibody (anti-CM-1.4 or anti-M1a) to UCD 3 125I-17S Ig. CM-1.4 appears to be fully expressed on 7S subunits but is altered on H chains. In contrast, anti-M1a bound both 7S subunits and H chains with decreased avidity indicating that the M1a specificity was altered in both preparations. Since CM-1.4 and M1a are present on 17S Ig H chains, and absent from 7S Ig, they probably represent allotypic markers in the constant region of 17S Ig H chains. Having assigned two 17S Ig allotypic specificities to H chains, we propose that the locus controlling their expression be called CM-1. Based on the distribution of the CM-1.4 and M1a allotypes in inbred lines of chickens, 3 alleles are defined at the CM-1 locus.

Alleles

Demonstration of an idiotypic antigen on a monoclonal cold agglutinin and on its isolated heavy and light chains.

A potent anti-idiotype serum produced in a rabbit immunized with the isolated heavy chains of an IgM cold agglutinin "Col" was rendered specific by solid-state adsorptions. The anit-Col idiotype was shown to bind specifically to both isolated Col heavy (mu) and light (kappa) chains as well as to intact Col IgM by three methods: (i) reversal of anti-idiotype inhibition of Col cold agglutinin in an automated hemagglutination-inhibition assay system; (ii) adsorption of the anti-idiotype by affinity gels consisting of Col IgM, mu, or kappa chains covalently coupled to Sepharose 2B; (iii) binding of Col IgM and its isolated chains by an anti-idiotype affinity gel. Fragments of Col light chain lacking constant region determinants but still capable of inhibiting anti-idiotype were produced by limited pepsin digestion of the light chains. The finding of shared idiotypic determinants on isolated heavy and light chains of a monoclonal antibody suggests that these chains share a common sequence in a hypervariable region. As an extension of the gene insertion theory of Wu and Kabat, we postulate that genes coding for hypervariable regions may be available for insertion into the DNA for both heavy and light chains.

Agglutinins

Occurrence of slowly sedimenting components with mu chain antigenicity in normal adult and cord serum.

The occurrence of trace amounts of slowly sedimenting components with mu chain antigenicity was investigated in 8 normal adult sera and 4 sera from cord blood of new-born infants. Separation of these components from 19S IgM was obtained by density gradient ultracentrifugation. The fractions were studied by radioimmunoassay. The results suggest that slowly sedimenting components with mu chain antigenicity occur in normal adult serum in amounts located in the mug/ml range. Several components sedimenting with various speeds were identified, although their sedimentation coefficients were not measured. This fact suggests that not only the already described 7S IgM monomer exists in normal blood but that other modes of association between mu and L chains or mu chains fragments also occur. Sera from cord blood showed patterns similar to that of adults.

Adsorption

The class of surface immunoglobulin on virgin and memory B lymphocytes.

The class of surface immunoglobulin receptors for antigen on B cell precursors of different classes of antibody-forming cells was determined by utilizing a technique of class-specific antigen suicide. Spleen cells are first treated with a class-specific antiserum under conditions that result in the stripping of that class from the cell surface. The cells are then permitted to bind a highly radioactive trinitrophenyl (TNP)-conjugated protein, which leads to lethal irradiation of all TNP-specific B cells except those whose TNP receptors had been removed by the class-specific stripping of surface immunoglobulin. In this way, the class of antibody-forming cells resulting from TNP stimulation of B cells with different classes of surface immunoglobulin can be examined. It was found that the virgin B cell precursors of IgM-producing cells are two types: cells bearing IgM receptors only and those bearing both IgM and IgD receptors. All virgin B cells that gave rise to IgG1 antibody-forming cells had both IgM and IgD on their surfaces, demonstrating that an antigen-dependent switch from IgM and IgD to IgG1 production is a common feature of B cell maturation. In contrast, memory B cell precursors of IgG1 antibody-forming cells had predominantly IgG1 as their surface antigen receptor. The implications of these findings on current models of B cell maturation are analyzed.

Animals

Expression and function of I region determinants on immunocompetent cells. I. Selective expression of I-C region determinants on immune cells.

We have examined the cytotoxic activity of anti-Iak serum and complement on various immune functions of BALB/c (H-2d) cells. Since the cytotoxic action of this antiserum on H-2d cells defines specificity Ia.7, an I-C region product, we have looked at the selective expression of this antigen. We have mainly used the in vitro anti-Lac2 response to study the cells involved in the induction and regulation of antibody. The data presented here show that Ia.7 is present on both IgM and IgG precursor B cells and in lesser amounts on plaque-forming cells. The antiserum also recognizes with less efficiency a product on specific T suppressor cells, which is possibly coded for by the adjacent I-J subregion. Both fluorescence and functional tests indicate the absence of Ia.7 on macrophages. It is also lacking on T helper cells. When we tested the antiserum on the in vitro cytotoxic responses to alloantigens, we found that neither T effector cells nor their precursors were affected.

Animals

Functional differentiation of B lymphocytes in congenital agammaglobulinemia. II. Immunochemical analysis of the in vitro primary immune response.

Cultures of peripheral blood lymphocytes (PBL) in which specific hemolytic plaque-forming cells (HcPFC) had been induced were labeled with 14C-amino acids. Antigen-specific products in the culture supernatants were characterized by using indirect immune precipitation in conjunction with specific immunoabsorbents and/or gel filtration followed by SDS-polyacrylamide gel electrophoresis. After 5 days of culture with antigen (sheep red blood cells or ovalbumin) newly synthesized IgM and specific IgM antibody were demonstrated in culture supernatants from normal donors and from four out of five patients with congenital agammaglobulinemia (cAgamma). Secreted products bound specifically to antigen and pretreatment of labeled supernatants with anti-mu and anti-L chain antisera, but not with anti-gamma antiserum, prevented binding. Typical mu- and L chains constituted only a proportion of the anigen-binding peptides recognized by the anti-mu reagents. Induction of IgM antibody synthesis was dependent on the presence of antigen and was correlated with the generation of HcPFC. No major differences between the antigen-induced products of cAgamma and normal PBL were observed. These findings suggest that in the absence of terminal B cell differentiation in vivo, certain patients with cAgamma possess precursor cells that can respond to antigen in vitro with the synthesis of specific humoral products, including IgM antibody.

Absorption

Preparation of monospecific antiserums against porcine immunoglobulins, using agarose-linked immunosorbents.

Immunoglobulins IgG, IgA, and IgM were isolated from porcine serum and milk, and antiserums against the 3 immunoglobulin classes were prepared. Monospecificity of the antiserums for the gamma-, alpha-, and mu-chains was obtained by absorbing them in agarose-linked immunosorbent columns. These immunosorbents were prepared by linking IgG or IgA-IgM to CNBr-activated agarose. Contaminating anti-alpha2-macroglobulin antibodies in the anti-IgA and anti-IgM serums were removed with agarose-linked fetal globulins.

Absorption

Isolation and preliminary characterization of two varieties of low molecular weight immunoglobulin in the bullfrog, Rana catesbeiana.

Two varieties of low m.w. immunoglobulins have been isolated from the serum of Rana catesbeiana frogs. They are highly cross-reactive, although each also contains unique antigenic determinants. Since both low m.w. immunoglobulins were identified in the serum of 22 individual frogs, it was concluded that they are isotypic variants. The light chains of R. catesbeiana and mammalian high and low m.w. immunoglobulins are similar in electrophoretic mobility on polyacrylamide gels containing sodium dodecyl sulfate. The heavy chains of fropg high m.w. immunoglobulins have the mobility of mammalian mu-chains; the heavy chains of both variants of frog low m.w. immunoglobulins migrate between mammalian mu- and gamma-chains in approximately the position of mammalian alpha-chains. An unusual structural feature of the R. catesbeiana high ald low m.w. immunoglobulins is that the unreduced proteins are partially dissociated in sodium dodecyl sulfate.

Animals

Biological expressions of lymphocyte activation. V. Characterization of a soluble immune response suppressor (SIRS) produced by concanavalin A-activated spleen cells.

Supernatant fluids from murine spleen cell cultures incubated with concanavalin A for 48 hr contain a factor(s), soluble immune response suppressor (SIRS), which suppresses plaque-forming cell responses to sheep erythrocytes by murine spleen cells in vitro. In the present studies, some of the biochemical and biophysical properties of SIRS were investigated. SIRS was non-dialysable; the suppressive activity was stable at 56 degrees C for 30 min, but was destroyed by treatment at 70 degrees C for 30 min, 80 degrees C for 10 min, or at pH 2. The suppressive activity was not absorbed by the stimulating antigen, SRBC, or antisera against murine IgG or mu-chain, suggesting that SIRS does not contain immunoglobulin determinants. Murine spleen and thymus, but not kidney cells, however, absorbed SIRS activity. Enzyme treatments revealed that SIRS was resistant to DNase and RNase, but was destroyed by trypsin and chymotrypsin. In gel filtration with Sephadex G-100, SIRS activity eluted in the fraction corresponding to m.w. in the range between 48,000 and 67,000. With polyacrylamide gel electrophoresis, SIRS activity migrated in the region cathodal to albumin. Isopycnic centrifugation in a cesium chloride gradient suggested that SIRS is a glycoprotein. These supernatant fluids with SIRS activity were also found to contain macrophage migration inhibitory factor (MIF). In the experiments using gel filtration, polyacrylamide gel electrophoresis, and isopycnic centrifugation to fractionate supernatant fluids, SIRS and MIF activity were found in the same fractions, and to date we have been unable to dissociate definitively SIRS activity from MIF activity.

Absorption

Receptors for antigen on lymphoid cells. II. The nature of the molecule responsible for plaque-forming cell adherence.

The nature of specific adherence of rat anti-TNP PFC to TNP-GRBC has been investigated with PLL-fixed antigen monolayers as cellular immunoadsorbents and as plaque indicators. The immunoglobulin nature of the molecule responsible for PFC adherence is suggested by the fact that pretreatment of the PFC with rabbit anti-rat Ig antisera, but not anti-histocompatibility antisera, inhibits adherence. Removal of the adherence capacity of early PFC with the proteolytic enzymes papain and pronase, or by "capping" with anti-Ig is followed by slow regeneration of the ability to adhere, suggesting that adherence is due to membrane rather than secreted immunoglobulin, the latter being detectable within minutes after enzyme treatment. Several time-related events relating to PFC adherence were observed. 1) Both direct and indirect PFC are capable of specific adherence; the ability to adhere, however, tends to decline with time, especially after secondary immunization. 2) Although early PFC adherence is unaffected by trypsin treatment, later populations become increasingly sensitive. 3) Pretreatment of PFC at various times after primary immunization with antisera specific for rat mu-chain indicates that IgM and possibly early IgG-secreting PFC have mu heavy chains on their surface. These data suggest that the PFC membrane is progressively changing during the maturation of the antibody response.

Adsorption